What was the plan to escape the ship?

From the text:

Arthur and I were to steal silently to the captain's cabin, seize the pistols and cutlass, and as quickly as possible despatch him and the mate. Robert, with a club, was to stand by the door leading from the deck down into the cabin, and, in case of necessity, beat back the sailors, until we could hurry to his assistance. We were to proceed then as circumstances might require. Should the attack be so sudden and successful as to prevent resistance, the hatch was to remain barred down; otherwise the slaves were to be called up, and in the crowd, and hurry, and confusion of the time, we resolved to regain our liberty or lose our lives. I was then to assume the unaccustomed place of pilot, and, steering northward, we trusted that some lucky wind might bear us to the soil of freedom.